Journal of Rangeland

Background and Objective: Climate is one of the main factors in the diversity and spread of plant species, which also affects their characteristics. Therefore, climate change may cause severe changes in the distribution and spread of plant species and affect the tolerance limits and environmental factors affecting the distribution of species and their geographical expansion. Therefore, predicting the impact of future climate change on the distribution of valuable plant species is of great importance in their management, effective conservation, and assessment of the level of threats. This study was conducted with the aim of predicting the impact of climate change on the current and future geographical distribution of the medicinal species Teucrium polium L. in the rangelands of Kerman province.
Methodology: In order to conduct this research, in the spring and summer of 2024, 6 reference habitats of this species in Kerman Province were visited and, based on field visits and using GPS, the geographical coordinates of the presence points of the studied species were recorded. In the present study, modeling was performed in two time periods including the base period (present) and the future time period (2050). The environmental variables used in this study include 19 climatic variables, 3 physiographic variables and land use of the study area. In order to investigate and predict the distribution status of Teucrium polium L. in the future, two general circulation models HadGEM3-GC31-LL and MRI-ESM2-0 were used under two distribution scenarios of SSP245 and SSP585.Also, the existence of correlation between all environmental layers was examined by Pearson's statistical test in SPSS software, and from the pair of variables that had a correlation higher than 80 percent, one variable was removed according to expert opinion, and finally 10 variables were selected as input to the model. The maximum entropy model (MaxEnt) was used to predict the current and future distribution of the studied species, and the importance of each environmental variable was also determined through the Jackknife test. Then, by comparing the maps obtained now and in 2050 for the studied species, the areas of increased, decreased, or preserved habitats were determined by the geographic information system. The AUC index was used to evaluate the model in preparing a map of suitable locations for the studied species.
Results: Based on the AUC values obtained (AUC > 0.9), the performance of the MaxEnt model in predicting the distribution of Teucrium polium habitats in the study area was classified as excellent, with an AUC score of 0.974. The results also indicate that the most influential variables contributing to habitat suitability were slope percentage, precipitation of the coldest quarter, and mean temperature of the coldest quarter. Finally, according to the estimates obtained in the HadGEM3 GC31 LL general circulation model, by 2050, under the SSP245 scenario, 68.08 percent and under the SSP585 scenario, 68.93 percent of the species' suitable habitats will be reduced and 98.54 and 106.90 percent of the species' suitable habitats will be added, respectively. Also, based on the estimates obtained in the MRI ESM2 0 general circulation model, by 2050, under the SSP245 scenario, 43.94 percent and under the SSP585 scenario, 50.73 percent of the species' suitable habitats will be reduced and 84.21 and 99.72 percent of the species' suitable habitats will be added, respectively.
Conclusion: The results showed that Teucrium polium can exhibit a suitable response to drought stress by employing some defense mechanisms such as reducing plant height, accumulating proline and protein in aerial parts, and being influenced by a greater contribution of environmental factors like slope percentage, precipitation of the coldest quarter, and mean temperature of the coldest quarter. Based on this, it can acquire new suitable habitats for itself in the future, considering climate change.